Drizzle is really hard on the bees. It shortens their life dramatically, so don't drizzle your winter bees! It basically comes down to harmful to bees or harmful to frames....
Having said that... I have treated my hives that have the mann lake plastic frames in them and it didn't do anything more than discolor them slightly. I am quite against drizzle... The bees must ingest the acid as they clean it from themselves and each other.
From Randy Olivers Site;
Does vaporization hurt the bees?
Radetzki didn’t note increased bee mortality after winter treatment. Heinz Kaemmerer of Heilyser Technology Ltd. says: “We treated several colonies for 3 months during winter, once a week with the vaporizer and all colonies survived.” “With brood, colonies can be treated with the right amount of OA 3 to 4 times, a week apart; there is no harm to bees, queen or brood.” Medhat Nasr confirms that vaporized oxalic is very gentle to the bees.
//End quote.//
Again, a quote from Randy Olivers site;
Heinz Kaemmerer of Heilyser Technology says:
“You can treat your colonies with a liquid mixture of OA and sugar but be careful. The liquid acid shortens the life of the bees. There is no problem during summer because the bee’s life not longer than approximately 6 weeks. The problem starts with winter bees–do not treat your winter bees more than one time with liquid OA. When using liquid OA bees get wet and have to clean each other. The result is, the acid ends up in their stomach and during winter without a cleaning flight it shortens the life of the bees. Two treatments on winter bees might kill the colony. Liquid OA is a slow killer and bees will probably die after a few weeks or month instead reaching the next season.”
//End quote.//
Ahh, okay, I just realized your using a home made vaporizor... That explains things.